Adjustable interbody introducer device and method

ABSTRACT

Provided is a novel surgical instrument having an adjustable distal end that can securely engage an interbody for introduction of the interbody into an intervertebral space, can be adjusted before and during the surgical procedure to vary the angle of the distal end of the device and the angle of introduction of the interbody, and after positioning that interbody at the surgical site, can be easily disengaged and removed.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to devices and methods for use inorthopedic spine surgery. In particular, the present invention relatesto a device having at least two distinct articulating surfaces, thedevice being useful as an artificial disc replacement and a method ofimplanting that device using a posterior approach.

2. Background Art

The human spine is comprised of thirty-three vertebrae at birth andtwenty-four as a mature adult. Between each pair of vertebrae is anintervertebral disc, which maintains the space between adjacentvertebrae and acts as a cushion under compressive, bending androtational loads and motions. A healthy intervertebral disc has a greatdeal of water in the nucleus pulposus—the center portion of the disc.The water content gives the nucleus a spongy quality and allows it toabsorb spinal stress. Excessive pressure or injuries to the disc cancause injury to the annulus—the outer ring that holds the disc together.Generally, the annulus is the first portion of the disc that seems to beinjured. These injuries are typically in the form of small tears. Thesetears heal by scar tissue. The scar tissue is not as strong as normalannulus tissue. Over time, as more scar tissue forms, the annulusbecomes weaker. Eventually this can lead to damage of the nucleuspulposus. The nucleus begins to lose its water content due to thedamage—it begins to dry up. Because of water loss, the discs lose someof their ability to act as a cushion. This can lead to even more stresson the annulus and still more tears as the cycle repeats itself. As thenucleus loses its water content it collapses, allowing the two vertebraeabove and below to move closer to one another. This results in anarrowing of the disc space between the two vertebrae. As this shiftoccurs, the facet joints located at the back of the spine are forced toshift. This shift changes the way the facet joints work together and cancause problems in the facet joints as well.

When a disc or vertebrae is damaged due to disease or injury standardpractice is to remove part or all of the intervertebral disc, insert anatural or artificial disc spacer or interbody and construct anartificial structure to hold the effected vertebrae in place to achievea spinal fusion.

A major challenge of spine surgery is in the development of surgicalinstruments for the surgeon to use during the implantation of thedevices such as an artificial disc replacement or interbody. Theinstrumentation must be easy to use, effective, durable and mostimportantly, must not interfere with or cause further damage to thepatient's anatomy.

There is a particular need to provide a specifically designed surgicalinstrument that can safely be used in the process of implanting a discspacer or interbody between adjacent vertebrae and then easily disengagethe instrument from the implanted interbody.

SUMMARY OF THE DISCLOSURE

The present invention meets the above identified need by providing anovel surgical instrument device that effectively engages an interbodyfor introduction of the interbody into an intervertebral space and afterpositioning that interbody can be easily disengaged and removed from thesurgical site.

Also provided is a device having an adjustable angle distal end forintroducing an interbody into an intervertebral space wherein the distalend of the device is provided with an interbody grasping unit that cansecurely grasp the interbody for the process of implanting the interbodyand, upon completion of the introduction, can be easily disengaged fromthe implanted interbody.

Also provided is a device having an adjustable angle distal end forintroducing an interbody into an intervertebral space wherein theadjustable angle distal portion of the elongated device can beselectively directed to at least one angle away from the longitudinalaxis of the device and locked in that configuration.

Also provided is a device having an adjustable angle distal end forintroducing an interbody into an intervertebral space wherein the distalportion of the elongated device can be selectively directed to at leastone angle away from the longitudinal axis of the device, locked in thatconfiguration, and repeatedly unlocked and readjusted to other angles asrequired.

Also provided is a method of introducing an interbody into anintervertebral space using a device having an adjustable angle distalend, the distal end being capable of securely connecting to theinterbody prior to the implantation of the interbody and easilyreleasing from the interbody after the interbody is implanted in asubject.

Also provided is a kit containing at least one adjustable angleinterbody introducing device as disclosed herein and at least one otherorthopedic device or tool used in spine surgery procedures. The kit caninclude at least one interbody device.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the adjustable interbody introducerdevice will become apparent to one skilled in the art to which thepresent invention relates upon consideration of the followingdescription of exemplary embodiments with reference to the accompanyingdrawings, wherein:

FIG. 1 shows an isometric view of the device having an adjustable angledistal end for introducing an interbody into an intervertebral space.The adjustable angle distal end of the device is shown positioned at anangle that is slightly elevated above the longitudinal axis of thedevice.

FIGS. 2A-B show a side view and a top view, respectively of the deviceof FIG. 1.

FIG. 3 shows an enlarged detailed view of the interbody grasping unitextending from a truncated representation of the outer shaft and innershaft of the device.

FIG. 4 shows the disassembled components of the device in assemblyalignment less the handle and slap hammer connector.

FIG. 5 shows the components of the device, which are shown in FIG. 4,fully assembled with the handle and slap hammer connector in assemblyalignment.

FIG. 6 shows an enlarged cross-sectional side view of the interbodygrasping unit extending from a truncated representation of the outershaft of the device. An interbody device is shown secured in thegrasping unit.

FIG. 7 shows a side view of a threaded interbody connection shaft.

FIGS. 8A-C shows side views of the device having an adjustable angledistal end for introducing an interbody into an intervertebral space,wherein FIGS. 8A, 8B, and 8C, respectively represent only three examplesof the multiple angles to which the distal end of the device can beselectively directed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Detailed embodiments of the present invention are disclosed herein;however, it is understood that the following description and each of theaccompanying figures are provided as being exemplary of the invention,which may be embodied in various forms without departing from the scopeof the claimed invention. Thus, the specific structural and functionaldetails provided in the following description are non-limiting, butserve merely as a basis for the invention as defined by the claimsprovided herewith. The device described below can be modified as neededto conform to further development and improvement of materials withoutdeparting from the inventor's concept of the invention as claimed.

The device, as generally shown at 10 in FIGS. 1, 2A-B, 4, 5 and 8A-C isan interbody introducer having an adjustable angle distal end. Thedevice 10 has a proximal first end 12 and a distal second end 14. Asshown in FIG. 4, the device 10 includes a tubular inner shaft 16 havinga proximal inner shaft first end 18 and a distal inner shaft second end20 with an inner shaft lumen 22 extending the full length of the innershaft 16 and having an inner shaft entry portal 24 defined at the innershaft first end 18 by the circumferential inner shaft wall 26 and aninner shaft exit portal 28 defined at the inner shaft second end 20 bythe circumferential inner shaft wall 26.

As also shown in FIG. 4 the device 10 includes a tubular outer shaft 30having a proximal outer shaft first end 32 and a distal outer shaftsecond end 34 with an outer shaft lumen 36 extending the full length ofthe outer shaft 30 and having an outer shaft entry portal 38 defined atthe outer shaft first end 32 by the circumferential outer shaft wall 40and an outer shaft exit portal 44 defined at the outer shaft second end34 by the circumferential outer shaft wall 40.

The inner shaft 16 is sized and configured to easily fit within theouter shaft 30 so as to permit rotational movement about thelongitudinal axis of the device. As shown in FIGS. 1, 2A-B, 5 and 8A-C,the inner shaft 16 is provided with a handle 46 having a handle proximalfirst end 48 and a handle distal second end 50. The handle 46 isattached around at least a portion of the proximal first end 18 of theinner shaft 16. As shown in FIG. 5 the outer surface 52 of the first end18 of the inner shaft 16 can be provided with handle attachment threads54, which are complimentary to handle threads 56, which are defined onat least the distal portion of the inner wall 58 of the handle lumen 60.This threaded attachment of the distal second end 50 of the handle 46 tothe proximal first end 18 of the inner shaft 16 is preferred; however,other attachments, as are known in the art can be used without departingfrom the inventor's concept. Examples of other handle attachments caninclude, bayonet fittings, snap fittings, cotter pin attachments, andthe like. In addition to using a threaded attachment of the handle 46 tothe inner shaft 16, the handle 46 and the inner shaft 16 can be providedwith complimentary dowel holes 64, 66 and a securing handle dowel pin 67at or near the location of the threaded attachment.

Movement of the inner shaft 16 within the lumen 36 of the outer shaft 30is initiated by the manual rotation of handle 46, which is securelyconnected to the inner shaft 16 so as to directly transfer therotational movement of the handle 46 to the rotational movement of theinner shaft 16. This rotational movement of the inner shaft 16 withinthe lumen 36 of the outer shaft 30 effects the adjustment of therelative angle of the distal second end 14 to the longitudinal axis ofthe device 10 due to the unique articulating interaction of the slantgeometry of an outer shaft cam surface 70 at the distal second end 34 ofthe outer shaft 30 and the geometry of a grasping unit proximal contactsurface 72 of the grasping unit 74 of the device 10.

The grasping unit 74 of the device, as shown in detail in FIG. 3, isconnected to the distal second end 20 of the inner shaft 16 by anarticulating hinge 76 as shown in FIGS. 1, 2A, 3, 4, 5, 6 and 8A-C. Thearticulating hinge 76 includes complimentary grasping unit hinge arms 78that are attached to corresponding inner shaft hinge arms 80 by opposinggrasping unit hinge pins 82, 84. The articulating hinge 76 allowsmovement of the inner shaft 16 and the grasping unit 74 in multipleplanes in the same way as is commonly found in a universal type joint,which is well known in the art.

The outer shaft 30 is circumferentially disposed around the at least aportion of the inner shaft 16. The inner shaft 16 is sized andconfigured to freely rotate within the lumen 36 of the outer shaft 30.The distal second end 34 of the outer housing 30 is approximate to thelocation of the distal second end 20 of the inner shaft 16. Outer shaftgripping surfaces 31 are provided on the outer shaft to facilitate easeof operation of the device. The proximal first end 32 of the outer shaft30 is abutted against a proximally disposed angle locking ring 68. Asshown in FIG. 4, the locking ring 68 is secured to the inner shaft 16 bya locking ring dowel pin 86. Disposed between the distal inner surfaceof the locking ring 68 and the surface of the proximal first end 32 ofthe outer shaft 30 is a biased bearing assembly, generally shown at 88in FIG. 4. As is well known in the art, the biased bearing assembly 88includes multiple ball bearing units 90, each bearing 90 having acorresponding biasing element 92, a preferable example of which is acoil spring. As is well known in the art, the components of the assembly88, under compression from the biasing elements 92, are held in relativeposition one to the other by the securely affixed locking ring 68.Multiple indentations 94 (not directly shown) that correspond in number,in size and in arc radius to the multiple bearings 90 in the assembly 88can be defined in the inner surface of the locking ring 68. As is knownin the art, operation of the biased bearing assembly 88 requiresrotation of the outer shaft 30 around the inner shaft 16, that rotationbeing punctuated by movement of the biased bearings 90 from oneindentation 94 to the next such that the rotational movement isnaturally paused as each bearing 90 is biased into the next indentation94. The tactile feedback of this momentarily interrupted rotationattendant to the biased bearing assembly 88 is similar to a ratchetingeffect. In addition to a tactile sensation in the device 10, it iscommon for biased bearing assemblies to also produce an audibleindication of movement of the bearings 90 from one indentation 94 to thenext. When the movement is momentarily halted by the user, the biasingelements 92 provide measured resistance to further movement and thustend to hold the bearings in their respective indentations therebyserving to hold or lock the device 10 in its last selected position.

The grasping unit 74 at its proximal edge is provided with a cam surface96 that is configured to be in contact with the at least a portion ofthe distal edge 98 of the outer shaft 30 as the inner shaft 16 isselectively rotated within the lumen of the outer shaft 30. As bestshown in FIGS. 8A-C, the slant geometry of the distal edge 98 of theouter shaft varies in relative position to the grasping unit 74 camsurface 96 as the inner shaft 16 is rotated. The effect of this contactbetween the slant geometry of the distal edge 98 and the cam surface 96of the grasping unit 74 is to alter the angle of the grasping unit 74relative to the longitudinal axis of the device 10. With reference tothe discussion of the halting movement effect that results from rotationof the inner shaft 16 against the bias of the bias bearing assembly 88,it is apparent that as the inner shaft 16 is selectively rotated withinthe lumen of the outer shaft 30, the angle of the grasping unit 74 willvary in a corresponding and predictable fashion. As the relativerotation progresses, the biased bearing assembly 88 will momentarilyhalt and lock the angle of the grasping unit in place until additionalrotational force is manually applied to the device 10. The user can beprovided with tactile and audible feedback of all rotational movement ofthe device. Further, as shown in FIG. 1, indicia 100 of the degrees ofthe selected angle can be provided on the proximal portion of the outersurface of the outer shaft. For example, grasping unit angle valuesindicating the variance from the longitudinal axis of the device 10 of−10 degrees to +50 degrees can be provided. However, the range ofpossible angles of which the device 10 is capable of achieving isdetermined by the amount of slant formed along the distal edge 98 of theouter shaft 30 and therefore, the disclosed device 10 can bemanufactured to be capable of a wide range of angles.

In operation, the user can employ a driving instrument, such as asurgical hammer or slap hammer to facilitate placement of the interbodyinto the proper position in the intervertebral space. To facilitate thatlikely possibility, the handle 46 of the device 10 is provided with aslap hammer recess 102 in the distal end that is sized and configured toaccept a slap hammer connector 104 as is shown in FIG. 5. The slaphammer recess 102 can be communicate with and be continuous with thehandle lumen 60 so as to provide a through passage along thelongitudinal axis of the handle 46.

As shown in FIG. 7, an interbody connector shaft 106 within the lumen 22of the inner shaft 16 is sized and configured to easily rotate aroundthe long axis of the device and translate along the long axis of thedevice 10. The interbody connector shaft 106 can be manufacturedentirely or at least in its most distal portions of materials havinggood strength but being flexible such that the connector shaft 106 canbe repeatedly bent at different angles as shown in FIG. 7. The interbodyconnector shaft has a connector shaft first end 108 and a connectorshaft second end 110. The connector shaft first end 108 is provided witha tool receptacle 112 that preferably corresponds to a standard tool fortorque application, such as, for example, a screw driver. The connectorshaft second end 110 defines an interbody securing element, whichpreferably is a threaded protrusion that is sized and configured tocorrespond to a threaded receptacle defined in the end portion of aninterbody, as shown in FIGS. 3, 6, 7 and 8A-C. The connector shaft 106can be threaded into the interbody as shown in FIG. 6 by attaching atool, such as a screw driver, to the tool receptacle 112 and applytorque at the first end 108 of the connector shaft 106. Access to theconnector shaft tool receptacle 112 within the lumen of the inner shaft16 can be achieved through the handle lumen 60. Alternatively, as shownin FIGS. 1, 2A-B, 5 and 8A-C, rotational force can also be applied tothe interbody connector shaft 106 by manually turning a thumb wheel 114that can be securely fixed to the interbody connector shaft 106 by athumb wheel dowel pin 116. Visual and manual access to the thumb wheel114 is provide through a thumb wheel window 118 defined through aportion of the wall of the inner shaft 16. As shown in FIGS. 2, 4, 5 and8A-C the thumb wheel window 118 can preferably be defined throughopposing sides of the inner shaft 16 so as to expose opposite sides ofthe thumb wheel 114 and thereby optimize the user's access to the thumbwheel 114.

In the exemplary embodiment described herein, the grasping unit 74 isspecifically configured to grasp an interbody implanted in aTransforaminal Lumbar Interbody Fusion (TLIF). As such, the graspingunit is provided with an interbody seat 120 having a specific geometryto correspond to the shape of the interbody. In addition to the threadedportion of the connector shaft second end 110, which is best shown inFIGS. 3 and 6, the interbody seat 120 can be provided with a superiorarm 122 and an inferior arm 124 that can be configured to providecircumferential grasping of at least a portion of the interbody 126.

While the device is described herein as an example adapted for use as anadjustable interbody introducer and particularly is well suited for usein Transforaminal Lumbar Interbody Fusion (TLIF), it is within theinventors'understanding that the grasping element can be configured andadapted to conform to any implantable surgical device.

In use, a surgeon can employ the disclosed advice by securing theinterbody 126 to the grasping unit 74 of the device 10, making anincision in the subject, defining an approach path to the surgical site,preparing the intervertebral space to receive the interbody 126, andinserting the interbody 126 by adjusting the angle of the distal end ofthe device to the desired angle and repeating the insertion efforts asnecessary. Upon achieving the proper position for the interbody,releasing the interbody from the grasping unit and removing the devicefrom the surgical site.

The device 10 can be manufactured as integral components by methodsknown in the art, to include, for example, molding, casting, forming orextruding, and machining processes. The components can be manufacturedusing materials having sufficient strength, resiliency andbiocompatibility as is well known in the art for such devices. By way ofexample only, suitable materials cam include implant grade metallicmaterials, such as titanium, cobalt chromium alloys, stainless steel, orother suitable materials for this purpose. Some components of the devicecan be made from plastics, composite materials, and the like.

It is also within the concept of the present invention to provide a kit,which includes the adjustable interbody introducer disclosed herein.Additionally, a kit can include additional orthopedic devices andinstruments; such as for example, bone screws or plates, spinal rods,hooks or links and any instruments or tools associated therewith. Such akit can be provided with sterile packaging to facilitate opening andimmediate use in an operating room.

Each of the embodiments described above are provided for illustrativepurposes only and it is within the concept of the present invention toinclude modifications and varying configurations without departing fromthe scope of the invention that is limited only by the claims includedherewith.

What is claimed is:
 1. An adjustable interbody introducer comprising: aninner shaft having a through lumen, the inner shaft defining alongitudinal axis, an outer shaft having a through lumen, said lumen ofthe outer shaft being of sufficient diameter to permit said inner shaftto easily rotate within said lumen of said outer shaft, said inner shaftbeing at least partially disposed within said outer shaft, an interbodyconnector shaft being sized and configured to easily rotate within saidlumen of said inner shaft, said interbody connector shaft being at leastpartially disposed within said inner shaft, said interbody connectorshaft having a proximal first end comprising a tool receptacle andhaving a distal second end, said tool receptacle being accessible tocontact by a tool inserted through said inner shaft, an interbodygrasping unit, configured at one end to securely grasp an interbody andcapable of easily disengaging and releasing from said interbody asrequired and having a second end configured to attach to said second endof said interbody connector shaft, said grasping unit being pivotablewith respect to both said inner and outer shafts; an angled distal endof said outer shaft, said angled distal end being an angle orcombination of angles other than a right angle to the longitudinal axisand being in contact with a cam surface of said grasping unit, saidinner shaft being rotatable with respect to said outer shaft to movesaid cam surface along said angled distal end to provide a pivot forceto said grasping unit.
 2. The device of claim 1, further comprising athumb wheel fixedly connected to said interbody connector shaft andexposed to visual and manual contact through a thumb wheel windowdefined in the wall of said inner shaft, wherein manual rotation of saidthumb wheel effects manual rotation of said interbody connector shaft.3. The device of claim 2, wherein said interbody connector shaftterminates at said distal second end as a threaded protrusion sized andconfigured to attach to a corresponding threaded interbody device. 4.The device of claim 1, further comprising a handle with a distal andproximal end having a through handle lumen passing entirely through saidhandle from said distal end through said proximal end, said proximal endcomprising a slap hammer recess, said handle being connected to aproximal end of said inner shaft.
 5. The device of claim 4, furthercomprising a slap hammer connector sized and configured to fit withinsaid slap hammer recess.
 6. The device of claim 1, wherein said graspingunit is connected to said inner shaft by a hinged connection.
 7. Thedevice of claim 6, wherein said hinged connection is a universal typejoint.
 8. The device of claim 1, further comprising a biased bearingassembly, said biased bearing assembly comprising multiple bearings, acorresponding number of biasing elements, and a corresponding number ofindentations in the device corresponding to the size and shape of thebearings, said biased bearing assembly being fixedly connected to saidinner shaft and being in biased forced rotational contact with a surfaceportion of said outer shaft.
 9. The device of claim 1 in combinationwith an interbody.
 10. The device of claim 9, wherein said interbody isfor implantation in transforaminal lumbar interbody fusion.
 11. Thedevice of claim 1 further comprising angle indicia inscribed on saidouter shaft.
 12. The device of claim 11, wherein said indicia include arange of angles of −10 degrees to +50 degrees.
 13. A method ofintroducing an interbody to a surgical site, the method comprising:providing an interbody introducer, said introducer comprising: an innershaft having a through lumen, an outer shaft having a through lumen,said lumen of the outer shaft being of sufficient diameter to permitsaid inner shaft to easily rotate within said lumen of said outer shaft,said inner shaft being at least partially disposed within said outershaft, an interbody connector shaft being sized and configured to easilyrotate within said lumen of said inner shaft, said interbody connectorshaft being at least partially disposed within said inner shaft, saidinterbody connector shaft having a proximal first end comprising a toolreceptacle and having a distal second end, an interbody grasping unit,configured at one end to securely grasp an interbody and capable ofeasily disengaging and releasing from said interbody as required andhaving a second end configured to attach to said second end of saidinterbody connector shaft, said grasping unit being pivotable withrespect to both said inner and outer shafts, an angled distal end ofsaid outer shaft, said angled distal end being an angle or combinationof angles other than a right angle to the longitudinal axis and being incontact with a cam surface of said grasping unit, said inner shaft beingrotatable with respect to said outer shaft to move said cam surfacealong said angled distal end to provide a pivot force to said graspingunit; securing an interbody to the grasping unit, making an incision ina subject, defining an approach path to the surgical site, preparing theintervertebral space to receive the interbody, inserting the interbodyby adjusting an angle of the interbody grasping unit to a desired angleand repeating insertion efforts as necessary, positioning the interbodyas required, releasing the interbody from the grasping unit and removingthe introducer from the surgical site.
 14. A kit comprising, at leastone interbody introducer, said introducer comprising: an inner shafthaving a through lumen, an outer shaft having a through lumen, saidlumen of the outer shaft being of sufficient diameter to permit saidinner shaft to easily rotate within said lumen of said outer shaft, saidinner shaft being at least partially disposed within said outer shaft,an interbody connector shaft being sized and configured to easily rotatewithin said lumen of said inner shaft, said interbody connector shaftbeing at least partially disposed within said inner shaft, saidinterbody connector shaft having a proximal first end comprising a toolreceptacle and having a distal second end, an interbody grasping unit,configured at one end to securely gasp an interbody and capable ofeasily disengaging and releasing from said interbody as required andhaving a second end configured to attach to said second end of saidinterbody connector shaft, said grasping unit being pivotable withrespect to both said inner and outer shafts, an angled distal end ofsaid outer shaft, said angled distal end being an angle or combinationof angles other than a right angle to the longitudinal axis and being incontact with a cam surface of said grasping unit, said inner shaft beingrotatable with respect to said outer shaft to move said cam surfacealong said angled distal end to provide a pivot force to said graspingunit; and at least one other orthopedic device or tool used in spinesurgery procedures.
 15. The device of claim 1, wherein said interbodyconnector shaft is a flexible shaft extending through a center lumen insaid grasping unit, said interbody connector shaft being rotatable withrespect to said inner shaft, said outer shaft, and said grasping unitregardless of relative position of said grasping unit with respect toboth inner and outer shafts.
 16. The device of claim 1, furtherincluding a flexible connector shaft disposed in said inner shaft. 17.The device of claim 16, wherein said flexible connector shaft includes adistal end configured for releasable engagement with said interbody.